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- Isolation of a euryhaline microalgal strain, Tetraselmis sp CTP4, as a robust feedstock for biodiesel productionPublication . Pereira, Hugo; Gangadhar, Katkam N.; Schulze, Peter S.C.; Santos, Tamara; de Sousa, Carolina Bruno; Schueler, Lisa; Custódio, Luísa; Malcata, F. Xavier; Gouveia, Luísa; Varela, J.; Barreira, LuísaBioprospecting for novel microalgal strains is key to improving the feasibility of microalgae-derived biodiesel production. Tetraselmis sp. CTP4 (Chlorophyta, Chlorodendrophyceae) was isolated using fluorescence activated cell sorting (FACS) in order to screen novel lipid-rich microalgae. CTP4 is a robust, euryhaline strain able to grow in seawater growth medium as well as in non-sterile urban wastewater. Because of its large cell size (9-22 mu m), CTP4 settles down after a six-hour sedimentation step. This leads to a medium removal efficiency of 80%, allowing a significant decrease of biomass dewatering costs. Using a two-stage system, a 3-fold increase in lipid content (up to 33% of DW) and a 2-fold enhancement in lipid productivity (up to 52.1 mg L-1 d(-1)) were observed upon exposure to nutrient depletion for 7 days. The biodiesel synthesized from the lipids of CTP4 contained high levels of oleic acid (25.67% of total fatty acids content) and minor amounts of polyunsaturated fatty acids with >= 4 double bonds (< 1%). As a result, this biofuel complies with most of the European (EN14214) and American (ASTM D6751) specifications, which commonly used microalgal feedstocks are usually unable to meet. In conclusion, Tetraselmis sp. CTP4 displays promising features as feedstock with lower downstream processing costs for biomass dewatering and biodiesel refining.
- Industrial production of Phaeodactylum tricornutum for CO2 mitigation: biomass productivity and photosynthetic efficiency using photobioreactors of different volumesPublication . Quelhas, Pedro M.; Trovao, Mafalda; Silva, Joana T.; Machado, Adriana; Santos, Tamara; Pereira, Hugo; Varela, João; Simoes, Manuel; Silva, Joana L.The photosynthetic efficiency (PE) and potential of Phaeodactylum tricornutum for CO2 mitigation in industrial tubular photobioreactors (PBRs) of different volumes were evaluated. A preliminary assay was performed at lab-scale to optimize the salt concentration of the culture medium. Interestingly, salinity did not affect the growth of P. tricornutum at concentrations of 2.5, 5, 10, and 20 g L-1. Higher volumetric productivities were achieved in the 2.5-m(3) tubular PBR (0.235 g L-1 day(-1)), followed by 35- and 10-m(3) PBRs. Maximum areal productivities corresponded to 48.5, 45.0, and 12.8 g m(-2) day(-1) for the 35-, 10-, and 2.5-m(3) PBRs, respectively. PE was thus higher in the 35- and 10-m(3) PBRs (2.21 and 2.08%, respectively). The 10- and 35-m(3) PBR showed CO2 mitigation efficiencies of 60 and 41%, respectively, of the CO2 introduced into the PBR, corresponding to 2.3 and 2.5 g of fixed CO2 per g of biomass. Overall, cultivation of P. tricornutum couples high PE and areal productivity when the industrial PBRs were used, particularly PBRs of larger volumes. This improved PE performance with larger PBR volumes strongly suggests that large-scale cultivation of this diatom holds great potential for industrial CO2 mitigation.
- Nutritional potential and toxicological evaluation of tetraselmis sp. CTP4 microalgal biomass produced in industrial photobioreactorsPublication . Pereira, Hugo; Silva, Joana; Santos, Tamara; Gangadhar, Katkam N.; Raposo, Ana; Nunes, Cláudia; Coimbra, Manuel A.; Gouveia, Luísa; Barreira, Luísa; Varela, JoãoCommercial production of microalgal biomass for food and feed is a recent worldwide trend. Although it is common to publish nutritional data for microalgae grown at the lab-scale, data about industrial strains cultivated in an industrial setting are scarce in the literature. Thus, here we present the nutritional composition and a microbiological and toxicological evaluation of Tetraselmis sp. CTP4 biomass, cultivated in 100-m3 photobioreactors at an industrial production facility (AlgaFarm). This microalga contained high amounts of protein (31.2 g/100 g), dietary fibres (24.6 g/100 g), digestible carbohydrates (18.1 g/100 g) and ashes (15.2 g/100 g), but low lipid content (7.04 g/100 g). The biomass displayed a balanced amount of essential amino acids, n-3 polyunsaturated fatty acids, and starch-like polysaccharides. Significant levels of chlorophyll (3.5 g/100 g), carotenoids (0.61 g/100 g), and vitamins (e.g., 79.2 mg ascorbic acid /100 g) were also found in the biomass. Conversely, pathogenic bacteria, heavy metals, cyanotoxins, mycotoxins, polycyclic aromatic hydrocarbons, and pesticides were absent. The biomass showed moderate antioxidant activity in several in vitro assays. Taken together, as the biomass produced has a balanced biochemical composition of macronutrients and (pro-)vitamins, lacking any toxic contaminants, these results suggest that this strain can be used for nutritional applications.
- Searching for new sources of innovative products for the food industry within halophyte aromatic plants: In vitro antioxidant activity and phenolic and mineral contents of infusions and decoctions of Crithmum maritimum L.Publication . Pereira, Catarina Guerreiro; Barreira, Luísa; Neng, Nuno da Rosa; Florencio Nogueira, Jose Manuel; Marques, Catia; Santos, Tamara; Varela, J.; Custódio, LuísaAromatic halophyte plants are an outstanding source of bioactive compounds and natural products with potential use in the food industry. This work reports the in vitro antioxidant activity, toxicity, poly phenolic profile and mineral contents of infusions and decoctions from stems, leaves and flowers of Crithmum maritimum L, an aromatic and edible maritime halophyte (sea fennel). Aspalathus linearis (Burm.f.) Dahlg. (rooibos) herbal tea was used as a reference. Sea fennel's tisanes, particularly from leaves, were rich in phenolic compounds and five of them (p-hydroxybenzoic and ferulic acids, epicatechin, pyrocatechol and 4-hydroxybenzaldehyde) were here described in C maritimum for the first time. Chlorogenic acid was the dominant phenolic determined. Na was the most abundant mineral in all tisanes followed by Ca and Mg in leaves' tisanes and K in flowers. Sea fennel's samples had a similar antioxidant activity than those from A. linearis, and had no significant toxicity towards four different mammalian cell lines. Altogether, our results suggest that sea fennel can be a source of products and/or molecules for the food industry with antioxidant properties and minerals in the form, for example, of innovative health-promoting herbal beverages.
- Natural products from marine invertebrates against Leishmania parasites: a comprehensive reviewPublication . Oliveira, Marta; Barreira, Luísa; Gangadhar, Katkam N.; Rodrigues, Maria Joao; Santos, Tamara; Varela, J.; Custódio, LuísaParasitic infections by Leishmania parasites remains a severe public health problem, especially in developing countries where it is highly endemic. Chemotherapy still remains a first option for the treatment of those diseases, despite the fact that available drugs exhibit a variety of shortcomings. Thus, innovative, less toxic more affordable and effective antileishmanial agents are urgently needed. The marine environment holds an immeasurable bio- and chemical diversity, being a valuable source of natural products with therapeutic potential. As invertebrates comprise about 60 % of all marine organisms, bioprospecting this class of organisms for antileishmanial properties may unravel unique and selective hit molecules. In this context, this review covers results on the literature of marine invertebrate extracts and pure compounds evaluated against Leishmania parasites mainly by in vitro methods. It comprises results obtained from the phyla Porifera, Cnidaria, Bryozoa (Ectoprota), Mollusca, Echinodermata, Annelida, Cetnophora, Platyhelminthes, sub phyla Crustacea (phylum Arthropoda) and Tunicata (phylum Chordata). Moreover, structure-activity relationships and possible mechanisms of action are mentioned, whenever available information is provided. About 70 species of marine invertebrates belonging to seven different phyla are included in this work. Besides a variety of crude extracts, a total of 140 pure compounds was tested against different Leishmania species. Although the research on the antileishmanial potential of marine invertebrates is in its early beginnings, promising results have been achieved that encourage further research. As more extracts and compounds are being screened, the possibility of finding active and selective antileishmanial molecules increases, rising new hope in the search for new treatments against leishmaniases.
- Urban wastewater treatment by Tetraselmis sp CTP4 (Chlorophyta)Publication . Schulze, Peter S.C.; Carvalho, Carolina F. M.; H., Pereira; Gangadhar, Katkam N.; Lisa Schueler, Lisa M. Schueler; Santos, Tamara; Varela, J.; Barreira, LuísaThe ability of a recent isolate, Tetraselmis sp. CTP4, for nutrient removal from sewage effluents before and after the nitrification process under batch and continuous cultivation was studied. Biomass productivities in both wastewaters were similar under continuous conditions ( 0.343 +/- 0.053 g L-1 d(-1)) and nutrient uptake rates were maximal 31.4 +/- 0.4 mg N L-1 d(-1) and 6.66 +/- 1.57 mg P-PO43 L- 1 d(-1) in WW before nitrification when cultivated in batch. Among batch treatments, cellular protein, carbohydrate and lipid levels shifted with aging cultures from 71.7 +/- 6.3 to 29.2 +/- 1.2%, 17.4 +/- 7.2 to 57.2 +/- 3.9% and 10.9 +/- 1.7 to 13.7 +/- 4.7%, respectively. In contrast, CTP4 cultivated continuously in Algal medium (control) showed lower biomass productivities ( 0.282 g VSS L-1 d(-1)) although improved lipid content (up to 20% lipids) in batch cultivation. Overall, Tetraselmis sp. CTP4 is promising for WW treatment as a replacement of the costly nitrification process, fixating more nutrients and providing a protein and carbohydrate-rich biomass as by-product. (C) 2016 Elsevier Ltd. All rights reserved.
- Scale-up and large-scale production of Tetraselmis sp CTP4 (Chlorophyta) for CO2 mitigation: from an agar plate to 100-m(3) industrial photobioreactorsPublication . Pereira, Hugo; Paramo, Jaime; Silva, Joana; Marques, Ana; Barros, Ana; Mauricio, Dinis; Santos, Tamara; Schulze, Peter; Raul J Barros; Gouveia, Luisa; Barreira, Luísa; Varela, J.Industrial production of novel microalgal isolates is key to improving the current portfolio of available strains that are able to grow in large-scale production systems for different biotechnological applications, including carbon mitigation. In this context, Tetraselmis sp. CTP4 was successfully scaled up from an agar plate to 35-and 100-m(3) industrial scale tubular photobioreactors (PBR). Growth was performed semi-continuously for 60 days in the autumn-winter season (17th October -14th December). Optimisation of tubular PBR operations showed that improved productivities were obtained at a culture velocity of 0.65-1.35 m s(-1) and a pH set-point for CO2 injection of 8.0. Highest volumetric (0.08 +/- 0.01 g L-1 d(-1)) and areal (20.3 +/- 3.2 g m(-2) d(-1)) biomass productivities were attained in the 100-m(3) PBR compared to those of the 35-m(3) PBR (0.05 +/- 0.02 g L-1 d(-1) and 13.5 +/- 4.3 g m(-2) d(-1), respectively). Lipid contents were similar in both PBRs (9-10% of ash free dry weight). CO2 sequestration was followed in the 100-m(3) PBR, revealing a mean CO2 mitigation efficiency of 65% and a biomass to carbon ratio of 1.80. Tetraselmis sp. CTP4 is thus a robust candidate for industrial-scale production with promising biomass productivities and photosynthetic efficiencies up to 3.5% of total solar irradiance.
- Growth performance, biochemical composition and sedimentation velocity of Tetraselmis sp. CTP4 under different salinities using low-cost lab- and pilot-scale systemsPublication . Trovão, Mafalda; Pereira, Hugo; Silva, Joana; Páramo, Jaime; Quelhas, Pedro; Santos, Tamara; Silva, Joana T.; Machado, Adriana; Gouveia, Luísa; Barreira, Luísa; Varela, JoãoBiomass harvesting is one of the most expensive steps of the whole microalgal production pipeline. Therefore, the present work aimed to understand the effect of salinity on the growth performance, biochemical composition and sedimentation velocity of Tetraselmis sp. CTP4, in order to establish an effective low-cost pilot-scale harvesting system for this strain. At lab scale, similar growth performance was obtained in cultures grown at salinities of 5, 10 and 20 g L-1 NaCl. In addition, identical settling velocities (2.4-3.6 cm h-1) were observed on all salinities under study, regardless of the growth stage. However, higher salinities (20 g L-1) promoted a significant increase in lipid contents in this strain compared to when this microalga was cultivated at 5 or 10 g L-1 NaCl. At pilot-scale, cultures were cultivated semi-continuously in 2.5-m3 tubular photobioreactors, fed every four days, and stored in a 1-m3 harvesting tank. Upon a 24-hour settling step, natural sedimentation of the microalgal cells resulted in the removal of 93% of the culture medium in the form of a clear liquid containing only vestigial amounts of biomass (0.07 ± 0.02 g L-1 dry weight; DW). The remaining culture was recovered as a highly concentrated culture (19.53 ± 4.83 g L-1 DW) and wet microalgal paste (272.7 ± 18.5 g L-1 DW). Overall, this method provided an effective recovery of 97% of the total biomass, decreasing significantly the harvesting costs.
- Incorporation of selenium on microalgae as supplement to artemia and zebrafishPublication . Santos, Tamara; Barreira, Luísa; Varela, J.Selenium (Se) is an essential element known to promote the health of humans and animals. This micronutrient is commonly used in aquaculture as a feed additive to enhance growth and larval antioxidant capacity and prevent skeletal deformities. Microalgae contain valuable micronutrients (e.g. PUFA, carotenoids) and are able to convert inorganic to organic Se, making them a suitable aquaculture feed source. Thus, the aim of this work was to produce Se-enriched Isochrysis galbana microalgal biomass to improve the contents of this element at different trophic levels in aquaculture. For this purpose, Se-enriched yeast and Seenriched microalgae in microdiets were assessed in terms of the biological performance and osteological development of zebrafish (Danio rerio) larvae. I. galbana was able to incorporate up to 150 mg Se Kg-1 DW when exposed to 20 mg Se L-1 in the medium, whereas concentrations higher than 25 mg Se L-1 inhibited growth. After feeding Se-enriched I. galbana to Artemia spp., the latter accumulated up to 20 mg Se Kg-1 DW compared to the non-enriched control (2 mg Se Kg-1 DW). Inorganic Se salts were found to be toxic to the larval stages at 5 mg Se kg-1. There were no significant differences between the treatments containing 0.5 mg Se kg-1 supplied through yeast and microalgal sources. In addition, the diet with Se-enriched microalgal biomass with a concentration of 2 mg Se kg-1 enhanced length, weight and significantly decreased skeletal deformations in zebrafish as compared to diets containing Se-enriched yeast or non-supplemented diets. Taken together, the results of the present work strongly suggest that I. galbana can be used to produce Se-enriched biomass for fish nutrition in the form of feed supplements.
- Effect of light quality supplied by light emitting diodes (LEDs) on growth and biochemical profiles of Nannochloropsis oculata and Tetraselmis chuiiPublication . Schulze, Peter S.C.; Pereira, Hugo; Schueler, Lisa; Guerra, Rui Manuel Farinha das Neves; Barreira, Luísa; Perales, Jose A.; Varela, João; Santos, TamaraBiochemical components obtained by microalgal biomass can be induced by specific wavelengths and processed to high value food/feed supplements or pharma- and nutraceuticals. Two biotechnologically relevant microalgae, Nannochloropsis oculata and Tetraselmis chuii, were exposed to non-tailored LEDs light sources emitting either mono- or multichromatic light with low red but significant blue (<450 nm) photon content, or tailored light sources with high blue or high red photon emissions: fluorescent light (FL), di- or multichromatic LED mixes. Growth of N. oculata and T. chuii under tailored light resulted in a approximate to 24% increase of the average biomass productivity as compared to cultures lit by non-tailored light sources. FL induced the highest C:N ratios in both algae (N. oculata: 7.91 +/- 0.09 and T. chuii: 11.29 +/- 0.03), highest total lipid (48.37 +/- 1.07%) in N. oculata and carbohydrate (55.31 +/- 1.02%) in T. chuii biomass. Among non-tailored light sources, monochromatic LEDs with emission peaks 465, 630 and 660 nm induced a approximate to 29% increase of carbohydrates and a approximate to 20% decrease of protein levels as compared to LEDs peaking at 405 nm and cool-and warm white LEDs. In conclusion, as FL have low photon conversion efficiencies (PCE), particularly within the red wavelength range, LEDs emitting at the 390-450 and 630-690 nm wavebands should be combined for optimal carbon fixation, nitrogen and phosphate uptake. (C) 2016 Elsevier B.V. All rights reserved.